EGR vs. SCR, Round 2

The 2010 "EGR vs. SCR" emission control system debate has taken some interesting turns in recent days. The big news is that Navistar has filed a lawsuit against the EPA, because way back in 2001 the Agency expressed misgivings about whether Selective Catalytic Reduction (SCR) could meet its 2010 diesel emissions standards. Navistar, which has eschewed SCR in favor of "Massive EGR" to meet the 2010 standards, claims that the EPA has failed to properly explain and document why it is now willing to certify SCR systems. You can guess how all the other engine manufacturers are responding... Meanwhile, in a survey of our own readers, we found that, of those fleet maintenance managers who have decided which 2010 engine technology they'll be using, the majority are sticking with Massive EGR over SCR. It bears mentioning that over two-thirds of the respondents were undecided; of the remainder, 20% said they were sticking with EGR, while only 13% said they had chosen SCR. It's too early to say if that's where the industry as a whole will be heading, but it certainly raises some questions about how things will shake out in 2010. Finally, in the 2007 emissions flashback department, I recently got a letter from a reader who is very worried about what is going to happen when the DPFs in his 2007 trucks all need to be removed for cleaning... We'll be looking at that issue in our August issue, but I'm wondering if anyone else is losing sleep over their 2007 and/or 2010 emissions system worries...